I claim the ornamental design for a canopy anchor, as shown and described.
FIG. 1 is a front view of the canopy anchor.
FIG. 2 is a rear view of the claimed design.
FIG. 3 is a left side view of the claimed design.
FIG. 4 is a right side view of the claimed design.
FIG. 5 is a top view of the claimed design.
FIG. 6 is a bottom view of the claimed design.
FIG. 7 is a perspective view of the claimed design; and,
FIG. 8 is a perspective view of the claimed design showing the end use with a canopy. The broken lines appearing on FIG. 8 of a canopy and lines are environmental matter forming no part of the claimed design.